1. Field of the Invention
This invention relates to the storage of electronic moisture sensitive devices (MSDs) prior to mounting onto a printed circuit board. More particularly, this invention relates to humidity-free enclosures for storing electronic moisture sensitive devices (MSDs) in a dry atmosphere thereby minimizing moisture damage to the MSDs prior to and while soldering them onto a printed board.
2. Description of the Background Art
The process for fabricating printed circuit board (PCB) assemblies for electronic equipment involves mounting electronic components onto the PCB and then heating the PCB in a solder re-flow oven, as in the case of surface mount devices, or in a wave solder machine, in the case of pin-through-hole devices. Unfortunately, electronic components are sensitive to moisture absorption during storage prior to being mounted onto the PCB. Such moisture absorption can frequently later result in damage to the components in the form of cracks due to thermal expansion, or moisture overpressure, of the residue moisture once the components are mounted onto the PCB and exposed to the high oven temperatures associated with the solder re-flow or wave-solder process. Once cracking occurs, air and moisture may contact the circuitry inside the package causing it to corrode and ultimately fail. It is therefore desirable that the electronic components be stored in a dry atmosphere before being mounted onto the PCB such that they will be as free of moisture as possible before they are mounted and soldered in place.
Presently there exist many ways to minimize the moisture damage to electronic components. One method involves subjecting the components to a slow bake process to drive out moisture prior to their mounting and soldering onto the PCB. However, the baking of the electronic components requires an extra step in the PCB fabrication process thereby increasing manufacturing time and cost.
Another method for minimizing moisture damage to electronic components comprises storing them in an enclosure providing a dry condition until just prior to mounting and soldering them onto the PCB. U.S. Pat. No. 6,622,399 entitled “Apparatus and Method for Maintaining a Dry Atmosphere to Prevent Moisture Absorption and Allow Demoisturization of Electronic Components” and U.S. Pat. No. 7,137,194 entitled “Apparatus and Method for Maintaining a Dry Atmosphere in Surface Mount Device Placement Machine”, the disclosure of each of which is hereby incorporated by reference herein, disclose known methods for minimizing moisture damage. Unfortunately, however, these storage enclosures involve exposing all the components in the enclosure to the ambient humid atmosphere when only one component is being withdrawn from the enclosure.
Therefore, one object of this invention is that it may provide an improvement which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the electronic component storage art.
Another object of this invention is that it may provide a storage enclosure employing single component packages stored in single storage compartments allowing a component to be removed from its storage compartment without interfering with any other component in another storage compartment of the enclosure assembly.
Another object of this invention is that it may provide a storage enclosure assembly employing single component packages stored in single storage compartments allowing a component to be loaded into its storage compartment without interfering with any other component in any other compartment of the storage enclosure.
The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Various embodiments of the invention may have none, some, or all of these mentioned objects. Accordingly, these objects or other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.